It is of common practice in the construction industry to use a flashing to seal the interstitial gap between the roof and a vertical member such as a pipe, a venting duct or a chimney passing through an aperture made in this roof.
In addition to ensuring weatherproofing of the roof aperture, the flashing is usually also devised to ensure proper drainage of the water that can accumulate on the roof.
Currently, a variety of roof flashings of different shape are available for weatherproofing an aperture made in a roof to allow passage of a vertical structure. FIGS. 1A to C show three examples of such flashings respectively called “flat flashing”, “gable flashing” and “pitched flashing”.
The flat flashing shown in FIG. 1A is commonly used for waterproofing an opening in a flat roof or building surface.
The gable flashing shown in FIG. 1B is used for weatherproofing an opening in the peak of an inclined roof.
Last of all, the pitched flashing shown in FIG. 1C is used for weatherproofing an opening on a an inclined roof, such as a pitched, lean-to, pavilion or gable roof. In the latter case, the surrounding member of the gable flashing which is usually of the conical shape must extend from the flat base of the flashing in such an inclined direction as to accommodate the roof slope.
In use, the flat base of the pitched flashing is positioned over the aperture made in the inclined roof and fastened on the same.
As is known, the roofs can be made of variety of materials, like for example tiles, stainless steel or other metal alloys, PVC or other polymeric materials, bitumen or fiberglass. Some of these roof materials can also be in the form of corrugated sheets. In the latter case, condensation and moisture can accumulate in their grooves. When used to insulate a roof covered with a corrugated material, pitched flashings of conventional structure, viz. with a flat base, may obstruct these grooves and thus not allow efficient drainage of water that may accumulate. Furthermore, the installation of such flashings can be problematic depending on the shape of the ridges on the roof material.